Are you having noises now, or before? Not sure about the Colorado set up, but some have a Crush Sleeve in there that sets the preload, and if it’s not set right, you will have noise and the gear mesh pattern will not be correct. That job is best left to professionals that are well trained in that. It sounds like just remove a bad seal and install a new one, but there is more to it than that. If you are having noise since, I would take it to someone that has experience and check why you are having noise, before damage is done. I have done that recently and had problems, and have decided to pay someone else with experience. It’s cheaper paying them first than having to take it in after you tried. They do not like fixing someone’s screw up. You wouldn’t either.